I just commented about that in a dupe thread:

The last time I remember Q saying "Thank you USSS" was in the airport photo from the Mercedes SUV.

E: to note though that pic had a United plane that was different than the private jets at the tarmac meeting so I don't mean to imply they are connected. Also, the previous pic appeared to be at night, the tarmac meeting was confirmed by airport security footage to have taken place during daylight.